Orienting systems



ORIENTING SYSTEMS April 27, 1965 J. T. DEwAN 3,180,409

ORIENTING SYSTEMS Filed Sept. 29. 1959 2 Sheets-Sheet 2 4/0/1/7 7`. wan INVENTOR.

Wuafw ATTORNEY United States Patent 3,180,409 ORIENTING SYSTEMS John T. Dewan, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Sept. 29, 1959, Ser. No. 843,244 6 Claims. (Cl. 166-4) This invention relates to methods of orienting and, more particularly, to methods for orienting the direction f tiring of a perforating apparatus in one of a plurality of tubing strings in a borehole.

Multiple well completion techniques are concerned with the problem of obtaining independent production from a plurality of producing zones from a single borehole where the zones are spaced vertically from one another.

In one technique of multiple well completion, after the borehole has been drilled, the tubing strings are positioned with their respective lower ends at each of the production zones involved and the entire borehole illed with cement so that each tubing string effectively serves as a casing. Selective perforation of the various production zones may then be accomplished by apparatus disclosed in a copending application of M. P. Lebourg, Serial No. 760,138, tiled September 10, 1958, and now abandoned in favor of application Serial No. 816,993 filed May 29, 1959, now Patent No. 3,168,141. Briefly described, a perforating apparatus in the aforesaid application is provided with an orienting means arranged to cooperate and align with a special locating collar inserted in a preselected position in a tubing string. The perforating or ring axis (or axes) of the perforating apparatus is located with respect to the orienting means and collar so as to avoid perforation of adjacent coextending tubing strings. While this apparatus is highly successful `and satisfactory, it does require that the locating collar be positioned in a tubing string at the time the string of tubing goes into the well.

Another type of selective perforation for dual tubing strings in a well bore is disclosed in copending application Serial No. 795,099, liled February 24, 1959. In this application there is disclosed an apparatus which employs a directional radioactivity source associated `in a predetermined relationship to the perforating axis (or axes) of a gun which is disposed in one tubing, while at the same level in another tubing, a radioactivity detector is disposed. The directional radioactivity source is adapted to be indexed relative to the tubing string in a predetermined manner so that the detector responds to radioactivity as the directional source is rotated relative to the string to obtain indications of the variations by radioactivity. Thus, the orientation of the radioactivity source relative to the detector may be determined and the source together with the perforating axis may then be directed so as to avoid interference with any adjacent tubing string. While this apparatus is commercially satisfactory, it is readily apparent that at least two winches and cables are required to lower the individual apparatus into the individual tubing strings. Therefore, it will be appreciated that a system for orienting the perforating apparatus which requires only one cable has definite advantages.

It is accordingly an object of the present invention t0 provide new and improved methods of orienting the firing axis of a perforating apparatus used in a multiple well completion.

Another object of the present invention is to provide new and improved methods of orienting perforating apparatus for multiple well completion using a single cable.

These and other objects of the present invention are achieved, in a -borehole containing two or more strings of pipe, by emitting radioactivity-inducing radiation into the media surrounding the tubing at a given level. Thereafter, a perforating means having at least one laterally- ICQ extending zone in which perforations are not produced is aligned in a preselected manner with a directional energy detecting device and attached thereto. The energydetecting device is then disposed at the given radioactivated level. The detecting device and perforating means are then positioned at various rotative positions in the one tubing so that the induced activity in the adjacent string or strings of tubing may be selectively detected, thereby permitting location of any adjacent tubing strings by radioactivity measurements so that the perforator may be oriented to perforate in a selected direction.

The novel features of the present invention are set forth with particularity in the appended claims. The present invention both as to its organization and manner of operation together with further objects and advantages thereof may best be understood by way of illustration and example of certain embodiments which taken in conjunction with the accompanying drawings in which:

FIG. l is an elevational view of an apparatus by which the present invention may be practiced as disposed in a tubing cemented in a borehole;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a view taken in longitudinal cross section along line 3 3 of FIG. l;

FIG. 4 is a horizontal cross-sectional view taken along line 4 4 of FIG. 3;

FIG. 5 is a typical representation of indications obtained by a recording apparatus indicating various rotative positions of the tool in a string of tubing; and

FIG. 6 is a schematic representation of another embodiment of the present invention.

FIG. 7 is a partial plan view of a portion of the indexing system.

Referring now to the drawings, in FIG. l, a borehole 10 extends transversely through earth formations 12 and contains strings of pipe 14, 15 which extend coextensively of one another and may be cemented in place by a body of cement 16. The pipe strings, for example, may extend to production zones at diiIerent levels. As will be described hereinafter, it is desired to perforate a pipe string disposed adjacent to another pipe string. It will be understood, however, that while the present invention will be described with respect to two strings of pipe, it is also applicable to bore holes containing three or more strings of pipe.

An elongated tool 17 by which the present invention may be practiced is adapted to be lowered and suspended in tubing string 14 at the level to be perforated by means of an armored electrical cable 18. Cable 18 is spooled on a winch 19 which, in `a customary manner, serves to raise and lower the tool through the tubing. The tool 17 includes a conventional cable head attachment and collar locator 20, an indexing mandrel 21, a radiation orienting device Z2 and a perforating apparatus 23 which are interconnected endwise to one another to form a unitary assembly.

The indexing mandrel 21 is slidably received inside of a centralizer collar 25 which has centralizing springs 26 to frictionally engage with the inner Wall of the tubing 14 in a conventional manner. The indexing mandrel 21 and collar 25 are arranged so that upon longitudinal or reciprocal movement of the cable 18, the indexing mandrel 21 will rotate relative to the centralizer collar 25 and thus rotate the entire assembly relative to the tubing string. In this rotation device, the mandrel 21 is provided with circumferentially spaced Vertical slots 21a and inclined interconnecting slots 2lb. Collar 2S has an indexing pin 25a received in the slots system which is resiliently urged into contact with the bottom of the slots and cooperates with the inclined slots 2lb to cause the rotation of the mandrel 21 as the indexing pin is transferred between adjacent vertical slots 21a. Shoulders 21C, 21d in the slot system effect an irreversible transfer of the indexing pin from a vertical slot to an inclined slot and from an inclined slot to a vertical slot. Ramp portions 21e are provided in the slots 21a, 2lb to effect the transfer of the pin 25a from the bottom of a slot to an elevation where the pin passes over a shoulder and again contacts the bottom of a slot. For further details of the indexing mandrel and collar, reference may be made to the aforesaid Lebourg application Serial No. 795,099 or to a copending application of C. P. Lanmon, filed February 24, 1959, Serial No. 794,877, now Patent No. 3,154,147.

The perforating apparatus 23 may be any one of the presently known commercial devices which is adapted to pass through tubing. For example, shaped charge perforating means 26 may be disposed in a tubular housing 27 and be suitably interconnected in a well-known manner either for successive or simultaneous detonation. The tiring axes (indicated by the arrows 28, 29 in FIG. 2) of the perforating apparatus, that is, the axes along which the perforating jets travel are preferably phased at an angle of 30 on opposite sides of a longitudinal plane A which intersects the central axis of the tool assembly. With this arrangement, there will be a blind zone B of approximately 300 extending about the periphery of the perforating apparatus in which perforations are not produced, the zone B also extending longitudinally of the perforator. Obviously, the perforating axes 28, 29 may be arranged to be coincident so as to re only in one direction or can be aligned relative to one another in any preselected manner in harmony with the principles of the invention which hereinafter will be made more apparent.

The radiation orienting device 22 shown in more detail in FIG. 3 includes a tubular housing 30 constructed Vof a material such as steel relatively transparent to radiant energy such as gamma rays. Disposed within the lower end of housing 30 is a cylindrical shield 31 constructed of lead, for example, to block gamma radiation. Shield 31 has a vertically-elongated and narrow width opening or aperture 32 adjacent to a radiant energy detector 33, for example, a Geiger-Mueller tube, which responds to gamma radiation in a well-known manner. The opening 32 thus permits gamma radiation to be detected in an essentially vertical directional pattern. The shield 31 is oriented relative to the perforator 23 so that detector 33 detects in a directional radiation pattern (indicated by the arrow 36-FIG. 2) in a plane through a vertical axis of the housing which pattern essentially lies in plane A and is directed opposite to the direction to which the perforating jets will extend. A threaded connector 34 serves to secure the housing 30 to the perforator 23.

Electrical conductors are connected between the detector 33 and an electrical device 38 in the upper end of the housing 30, which electrical device includes a battery power supply and pulse amplier (FIG. 3). Shock absorbers 38a can be used to mount the pulse amplifier 38 relative to the housing 30. At the surface of the earth, an integrator 40 is coupled to a recorder 41. The recorder 41 has a recording medium which is driven each time the tool is indexed. The integrator 40 is coupled via cable 18 to the pulse amplifier in device 38 to derive electrical indications of the intensity of the radiation. The details and operation of the electrical device 38 may follow conventional practice as shown in the Johnson Patent No. 2,852,- 696 and thus a further description is deemed unnecessary.

Intermediate of the electrical device 38 and the shield 31 is a cylindrical member 42 which receives a neutron source 43 such as conventional radium-beryllium, polonium-beryllium, actinium-beryllium or like sources. The member 42 is also coated with a boron layer to provide a thermal neutron sink in the immediate vicinity of the tubing containing the tool thereby minimizing background activity of the tubing in which the tool is positioned. Also the neutron source 43 should be spaced a suicient distance from the detector to prevent direct detection of the gamma rays emitted by the neutron source or neutron captured gamma rays produced in the adjacent media, a distance of five or six feet being suitable.

In practicing the present invention the opening 32 for the detector 33 is aligned relative to the direction of the perforating axes 28, 29, for example, in the plane A as shown in FIG. 2. Thereafter the tool is passed through a tubing until the neutron source 43 is positioned just above or at the level to be perforated. The tool is allowed to remain stationary for, say, 15 minutes to an hour in this position during which time the neutron bombardment induces gamma ray activity in the surrounding media. The main activities induced are A128, having a half-life of 2.3 minutes, caused by bombardment of A127 and Si28 in the surrounding cement and formation, and Mn56 having a half-life of 2.6 hours caused by bombardment of Mn55 in adjacent steel tubings. When the Mn56 activity has built up suciently, the tool is raised so that the directional gamma detector 33 is positioned at the point of activation, and about 10 minutes is allowed to elapse thereby permitting the A128 activity to decay.

In a rst position of the radiation detecting device 33, some of the gamma radiation from the Mn56 activity passes through the aperture 32 and impinges on detector 33. The detector 33 produces pulse responses which occur at a rate dependent upon the intensity or ilux of the incident gamma radiation and such pulses are amplified in device 38 and supplied to integrator 40 which derives a potential representing the pulse rate. That potential is applied to recorder 41 so that a record of pulse rate is obtained. If the tool is, for example, initially positioned as shown in FIG. 2, a pulse rate indicated on a record such as by typical point 45 as shown in FIG. 5 may be obtained.

Since the centralizing springs 26 have suflicient frictional force to prevent the centralizer collar 25 from rotating, limited up and down movement of the cable 18 permits the radiation orienting device 22 and perforating means 23 to be rotated relative to the tubing 14 by the indexing mandrel 21 between successive rotative positions. As illustrated by points 46, 47 in FIG. 5, as the aperture 32 rotates away from the adjacent tubing, the indications obtained will decrease; and when the aperture 32 rotates towards the adjacent tubing, the indication will increase to the point 48 where the tool has been rotated through 360. At the proper location of perforating jets 28, 29 relative to the adjacent tubing (FIG. 2) the gun 23 may be red and the perforating jets 28, 29 will avoid the tubing 15.

It should be appreciated from the foregoing that the locations of the detecting device 33 and source 43 may be inverted, if desired, for convenience of construction and assembly.

In another aspect of the present invention, the orientation of a perforating apparatus may be achieved by use of a source 42 of radioactivity as described previously suitably spaced from an energy-selective detection system 50 (FIG. 6) such as a scintillation element 51 optically coupled to a photomultiplier 52. The source 42 and detection system 50 are disposed in a housing 30 in a similar manner to the arrangement described with respect to FIG. 3. The output of the photomultiplier 52 is conducted via a cable in a manner similar to that described with respect to FIG. l to an amplifier 53 located at the earths surface. The amplifier 53 is coupled to a pulseheight analyzer 54, the analyzer 54 being coupled to a recorder 44. In this system, by detecting the energy level of incident radiant energy on the scintillation element 51, the effect of Mn56 and A128 activities may be discriminated from one another so that the oriented indications in the Mn56 activities may be directly obtained without the necessity of moving the source and waiting for the decay of A128 activities. This is possible because the energy level of the gamma rays emitted by the A128 is 1.8 meV. while the predominant energy level of the gamma rays emitted by Mn56 is 0.8 mev. Thus, the pulse height analyzer is arranged to select pulses corresponding to the gamma ray level of 0.8 mev. and transmits a corresponding signal to the recorder 44. By providing a shielded aperture for the scintillation counter and coupling the counter to a perforating apparatus and an orienting device in a manner similar to that described with respect to FIG. l the directional intensities of radiation may be detected. In other respects the structure and operation of the apparatus is as above-described and thus need not be further elaborated upon.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. A method of orienting a perforating apparatus in a string of well pipe with respect to at least one object disposed in a media in the well bore outside the pipe comprising the steps of: irradiating a media and an object of different compositions characterized by different radioactive half-lives for a period of time wherein the media has a shorter half-life than an object, permitting the delayed radioactivity induced in the media to subside during a succeeding period of time, and subsequently detecting the direction in which a selected value of the remaining delayed radioactivity in an object exists after the radiation induced in the media has substantially decayed, and orienting a perforating apparatus in said pipe string with respect to the selected value.

2. In a method of orienting a zone of a perforating apparatus in which perforations are not produced, in a string of tubing relative to a coextending string of tubing wherein the strings of tubing are disposed in a well bore and surrounded by a media, the steps of: aligning a directional radiation detector relative to the zone of the perforating apparatus in which perforations are not produced, irradiating from one string of tubing the media and at least one adjacent string of tubing which have predominate compositions with different radioactivity half-lives at a level in the borehole through which at least two strings of tubing extend, permitting a period of time to elapse for the short-life radioactivity induced in the media to decay, detecting the remaining delayed radioactivity in the one adjacent string of tubing at a plurality of successive radial positions at the level of induced radiation in the one string of tubing, and obtaining indications of the detected remaining delayed radioactivity in the one adjacent string of tubing for the successive radial positions thereby to permit orientation of the perforating apparatus with respect to the one adjacent string of tubing.

3. In a method of orienting a zone of a perforating apparatus in which perforations are not produced, in a string of tubing relative to another coextending string of tubing wherein the strings of tubing are disposed in a well bore and surrounded by a media, the steps of: aligning a directional radiation detector relative to the zone of a perforating apparatus in which perforations are not produced, irradiating from one string of tubing a media and at least one adjacent string of tubing which have predominant compositions of dilierent radioactivity half-lives for a period of time at a level in the borehole through which at least two strings of tubing extend, permitting another period of time to elapse for the short-life radioactivity induced in the media to decay, detecting delayed radioactivity remaining from the one adjacent string of tubing at a plurality of successive radial positions at the level of induced radiation in the one string of tubing, and obtaining indications of the detected remaining delayed radioactivity for the successive radial positions thereby to permit orientation of the perforating apparatus with respect to the one adjacent tubing, positioning the zone of the perforating apparatus in which perforations are not produced in facing relationship to the one adjacent tubing whereby the perforating apparatus will avoid perforation of the one adjacent string of tubing.

4. In a method of orienting a zone of a perforating apparatus in which perforations are not produced, in a string of tubing relative to another coextending string of tubing wherein the strings of tubing are disposed in a well bore and surrounded by a media, the steps of aligning a directional gamma radiation detector relative to the zone of a perforating apparatus in which perforations are not produced, irradiating from one string of tubing a media and at least one adjacent string of tubing which have predominant compositions of different radioactive half-lives for a period of time with a source of neutrons ata level in the borehole through which at least two strings of tubing extend, removing the neutron source from the activated level and permitting another period of time to elapse for the short-life radioactivity induced in the media to decay, detecting remaining delayed radioactivity in the one adjacent string of tubing for a plurality of successive radial positions at the bombarded level, and obtaining indications of the detected remaining delayed radioactivity for the successive radial positions thereby to permit orientation of the perforating apparatus with respect to the one adjacent tubing.

5. A method of locating an object disposed in media adjacent to and exterior of a string of well pipe, wherein such object and the media are of different compositions characterized by dilerent radioactive half-lives and wherein the media have a shorter half-life than such object, comprising the steps of: irradiating for a period of time, media exterior to a string of pipe; and subsequently detecting, after a succeeding period of time during which delayed radioactivity induced in the media is permitted to subside, any delayed radioactivity remaining whereby the intensity of radioactivity remaining indicates either the presence or absence of said object at the level of irradiation.

6. In a well bore containing at least two strings of tubing embedded in a media with a characteristic shorter radioactive half-life than such tubing strings, a method of orienting, in one string of tubing relative to another string of tubing, a perforating apparatus having a lengthwiseextending zone in which perforations are not produced including the steps of: aligning a directional radiation detector relative to the zone of the perforating apparatus in which perforations are not produced; irradiating the media and another string of tubing from a position within one string of tubing by means of a source of neutrons for a period of time suiiicient for activation of such media and another string of tubing; subsequently, after another period of time adequate for decay of the delayed radiation in the mediato subside, detecting, at a succession of radial points relative to the one string of tubing, such delayed radioactivity which emanates primarly from another string of tubing; deriving indications of the intensity of such delayed radioactivity relative to a radial point in the one string of tubing; and orienting the directional radiation detector in accordance with the intensity indications thereby to orient the lengthwise-extending zone of the perforating apparatus relative to another string of tubing.

References Cited by the Examiner UNITED STATES PATENTS 2,147,544 2/39 Potts 166-66 2,220,509 11/40 Brons 250-83.6 2,228,623 1/41 Ennis 166-4 2,456,233 12/48 Wolf Z50- 43.5 2,469,461 5/49 Russell Z50- 83.6 2,667,583 l/54 Herzog Z50-43.5 2,998,068 8/61 True 166-55 CHARLES E. oCoNNELL, Primm-y Examiner.

BENJAMIN BENDETT, HARRISON R. MOSELEY,

Examiners. 

1. A METHOD OF ORIENTING A PERFORATING APPARATUS IN A STRING OF WELL PIPE WITH RESPECT TO AT LEAST ONE OBJECT DISPOSED IN A MEDIA IN THE WELL BORE OUTSIDE THE PIPE COMPRISING THE STEPS OF: IRRADIATING A MEDIA AND AN OBJECT OF DIFFERENT COMPOSITIONS CHARACTERIZED BY DIFFERENT RADIOACTIVE HALF-LIVES FOR A PERIOD OF TIME WHEREIN THE MEDIA HAS A SHORTER HALF-LIFE THAN AN OBJECT, PERMITTING THE DELAYED RADIOACTIVITY INDUCED IN THE MEDIA TO SUBSIDE DURING A SUCCEEDING PERIOD OF TIME, AND SUBSEQUENTLY DETECTING THE DIRECTION IN WHICH A SELECTED VALUE OF THE REMAINING DELAYED RADIOACTIVITY IN AN OBJECT EXISTS AFTER THE RADIATION INDUCED IN THE MEDIA HAS SUBSTANTIALLY DECAYED, AND ORIENT- 